Cooling water corrosion inhibition method

Abstract

A method of providing corrosion inhibition to copper, nickel, aluminum, zinc, tin, lead, beryllium, carbon steel, various alloys of such metals, and galvanized coatings in evaporative cooling water applications approaching zero liquid discharge that are specifically attacked by cooling water with residuals of corrosive chemistry or ions such as ammonia / ammonium ion, chloride, high TDS, OH−, or high pH. The method includes applying azoles inhibitors (such as TTA, BTA, etc.) at residuals of 0.25 mg / L to 200 mg / L or greater (as azoles) to the cooling water application and operating with a combination of high TDS (greater than 2500 mg / L) and high pH (greater than 9.0), while maintaining low total hardness (less than 200 mg / L as CaCO3).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Not ApplicableSTATEMENT RE: FEDERALLY SPONSORED RESEARCH / DEVELOPMENT[0002]Not ApplicableBACKGROUND[0003]This invention is directed toward corrosion inhibition in evaporative cooling water applications. More particularly, this invention is directed toward the use of azoles inhibitors in combination with high Total Dissolved Solids (TDS), high pH, and low total hardness.[0004]With respect to the inhibition of corrosion for metals benefiting from the discoveries disclosed herein, the most common examples cited are copper and copper alloys because of their good thermal and workability properties for heat transfer and fabrication, and their inherent properties for bio-fouling resistance and corrosion resistant oxide formation under water chemistry conditions addressed by prior art applications. More specifically, these discoveries focus on corrosion inhibitor performance in water chemistry conditions that are the result of evaporative cooling ...

AI Technical Summary

Benefits of technology

"The present invention relates to the use of azoles as inhibitors in evaporative cooling water applications. The invention addresses the problem of corrosion of various metals, such as copper, nickel, zinc, aluminum, and their alloys, in cooling water systems that have high TDS and pH levels. The invention proposes the use of azoles at a residual level of 0.25 mg / L to 200 mg / L to prevent corrosion caused by ammonia, ammonium ions, hydroxide ions, chloride ions, or sulfate ions. The invention also contemplates the use of azoles in combination with other corrosion inhibitors, such as silica-based corrosion inhibitors, to provide synergistic performance and prevent multiple metals from contributing to corrosion processes. The method may be used in evaporative cooling water systems that have high TDS and low CaCO3 levels. The invention provides a safer and effective solution for preventing corrosion in various cooling water systems."

Problems solved by technology

Corrosive attack of copper by ammonia in water is well known in the water treatment industry, and presents a particular challenge to reuse of wastewater sources that contain ammonia in cooling water systems that use copper and other metals and alloys which are vulnerable to ammonia.

In the presence of air and ammonia, aluminum brass is subject to stress corrosion cracking.

Ammonia also tends to increase the general corrosion rates of copper alloys.

Such systems do not typically control hardness at less than 200 mg / L (as CaCO3) as this condition increases water corrosiveness.

Inhibitor use and consumption by blow down wastage is significant, thus these application are costly and environmentally inefficient.

However, such applications of azoles in closed systems operate without high TDS concentrations in the cooling water since there is no evaporation and concentration of makeup water chemistry.

As such, inhibitor use and consumption are limited and their application is cost efficient.